HUGE polyethylene energy compensating manholes make usage of drop chambers obsolete in inclined terrain (hills). Energy compensating manholes can be of variable height and in Ø800, Ø1000 or Ø1250 mm diameters. High velocity rain water enters the chamber body tangentially, leaves its energy by flowing inside the chamber along a circular path and flow out of the base to connect to the main line. The neck can be cut along the marked cutting lines with a regular hand saw and the height of the chamber can be adjusted to grade.